Circuit breaker



1941- -P. DUFFING 2,231,703

CIRCUIT BREAKER Filed Aug. 22,1959

INVENTOR Paa/ fluff/ WITNESSES:

' J/f an/flv BY 212 WW ATTORN Patented Feb. 11, 1941 2,231,708

UNITED STATES PATENT OFFICE CIRCUIT BREAKER Paul Diifiing, Berlin-Siemensstadt, Germany, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 22, 1939, Serial No. 291,315 In Germany August 22, 1938 11 Claims. (Cl. 20082) The invention relates to circuit interrupters, multi-pole circuit breakers which insures that and more particularly to Operating mechanisms all of the breaker poles will be operated simulof the hydraulic type for high voltage circuit taneously even though air is present in the liquid breakers capable of interrupting a high power of the system.

electrical circuit. Another object of the invention is the pro- In the copending application of Fritz Kesselvision of an improved hydraulic operating mechring et al., Serial No. 254,614, filed February 4, anism for multi-pole circuit breakers in which 1939, and assigned to the assignee of the presmeans is provided for preventing the air dissolved ent invention, there is shown and described a in the liquid of the system from separating out hydraulic Operating mechanism or igh voltage of the liquid; thus insuring that all of the poles w multi-phase circuit breakers, in which the conwill be operated simultaneously. tact structure of each phase has a separate hy- In carrying out the invention, back pressure draulically actuated operating device connected valves or check valves are provided in one or mechanically thereto. The opening and closing more portions of liquid conductors of the hymovement of the operating devices is carried out draulic system. The valves connect the portion 15 by means of insulating qu d Columns ving or liquid conductor to a source of liquid pressure as power transfer means, which act on the ingreater than atmospheric pressure, thus maindividual operating pistons connected with the taining the liquid of the portion or portions of moving contacts of the breaker phases. the system at a pressure greater than atmos- For the satisfactory operation of such hypheric pressure and preventing the air dissolved 2o draulic drives, it is particularly important that in the liquid from separating out of the liquid. the driving liquid shall contain no air. The pro- The novel features that are considered characposal has already been made in the aforementeristic of the invention are set forth in pari d copending pp i to c rry ou the ticular in the appended claims. The invention Packing b e t e l q C du ng and the itself, however, both as to structure and oper- 25 air n ni parts f the rivin sy em by ation, together with additional objects and admeims 0f fleXible metallic beilOWS- such Packvantages thereof, will best be understood from i s a e es d for the purpose of preventing the following detailed description of several eme atmospheric air and the air C a d in t bodiments thereof when read in conjunction with 3 compressed air drive for the control piston from th accompanying dra ing, in which: entering the hydraulic system. Figure 1 is a sectional View, partly diagram- It has been found, however, that the liquid itmatic, of the circuit breaker operating mecha- Sel f t hydraulic System m y have air parnism of the present invention; and ticles dissolved therein. which have a tendency of Fig. 2 is a sectional view, partly diagrammatic,

separating Out Of the u S ch conditions of a modified form of the circuit breaker oper- 35 arise for one reason because of the fact that ating mechanism. co p y large moving qu d quantities are Referring to Figure l of the drawing, the mulinvo ve in the yd u c system, Which are disti-pole circuit breaker which is shown diagramplaced p y Over a comparatively large p matically as a two-pole breaker, comprises a pair thereby pr ducing a f m n th liqu d f t of movable contact members 5 and 1, one for 40 y The air Coming of the l q id reneach pole unit of the breaker. The contact memd the power transfer medium, the qui bers 5 and l are movable into and out of encompressible to a certain extent, or on the low gagement with cooperating stationary contacts pressure side produces a suction effect, thus pre- 9 and H, which are electrically connected in the venting the simultaneous operation of all of the separate lines [3 and I5. 45 poles or phases of the high voltage breaker. Although the invention is disclosed as a two- One apparent solution of the problem of prepole circuit breaker mechanism, it is to be unventing air emission from the liquid of the sytem derstood that the invention is applicable to a appears to be the use of specially treated liquids. breaker having any number of poles, and may be he u e Of u pp p y p eat d l quids, used to control a number of separate circuits, or

however, is not practical for a number of reathe lines of a multi-phase circuit. sons arising from the technique of the opera- The multi-pole circuit breaker may be of any tion. conventional construction, as for example, of the An object of the invention is the provision of construction disclosed in the copending applian improved hydraulic operating mechanism for cation of Fritz Kesselring et al., Serial No. 254,614, 55

filed February 4, 1939, and assigned to the assignee of the present invention.

The circuit breaker is operated by a hydraulic operating mechanism which is operable to effect simultaneous actuation of the two movable contact members 5 and 1 to open or to closed circuit position. The hydraulic operating mechanism comprises, in general, a pair of individual liquid actuated operating means indicated generally at l1 and I9, one for each of the movable contact members, for moving the contact members 5 and 1 to open and to closed circuit positions, and a liquid moving means or controlled pump means indicated generally at 2| for controlling the simultaneous operation of the two individual operating means l1 and I9.

Each of the individual liquid actuated operating means comprises an operating cylinder 23 preferably of metal, and an operating piston 25 which is reciprocably movable in the cylinder 23. The operating pistons 25 are mechanically connected directly to the movable contact members 5 and 1 respectively, by means of operating rods 21 and 29 which extend through packed openings provided therefor in the heads of the operating cylinders 23.

The liquid moving means or control pump means 2| comprises a metal pump cylinder 3| and a pump piston 33 which is reciprocably movable in the cylinder 3|.

The opposite ends of the pump cylinder 3| communicate with the opposite ends of the operating cylinders 23 through the agency of a pair of liquid carrying conductors 35 and 31, which comprise tubes of strong insulating material.

The hydraulic system is completely filled with an insulating liquid, for example, oil, chlorinized or fluorinized hydro-carbons or the like, which serves to transmit the force from the control pump means 2| to the operating pistons 25. The entire hydraulic system is made liquid-tight in a well known manner by providing suitable liquid-tight packings at the connections of various elements and for the openings in the cylinders.

The control pump piston 33 is adapted to be moved downwardly to efiect a circuit closing operation of the circuit breaker by means of an air pressure actuating device 39 which comprises a metal cylinder 4|, and an air pressure operated piston 43 movable in the cylinder 4|. The air pressure operated piston 43 is mechanically connected directly to the control pump piston 33 through the agency of a connecting rod 45 which extends through suitable packed openings provided therefor in the ends of the cylinders 3| and 4|. The upper end of the air pressure cylinder 4| communicates with a suitable source of compressed air (not shown) through the agency of an air pressure conducting tube 41, and through a suitable air pressure control valve (not shown). The control pump piston 33 is adapted to be moved upwardly to efiect simultaneous circuit opening operation of the several pole units of the circuit breaker by means of an accelerating spring 49 which is disposed in the lower portion of the air pressure cylinder 4|, and interposed between the lower end of the air pressure cylinder 4| and the air pressure operated piston 43.

A latching means is provided for releasably holding the circuit breaker in closed position. This latching means comprises a latch element 5! carried by the connecting rod 45 which is adapted to be engaged by a pivoted latch 53 pivotally mounted on the upper end of the pump cylinder 3|. The pivoted latch 53 is biased to latching position by means of a light spring 55,

and is adapted to be moved to released position 5 to eifect opening of the circuit breaker by means of an electromagnetic trip unit 51. The movable core or trip plunger of the trip unit 51 is pivotally connected to an extending arm 59 of the pivoted latch 53. The energizing winding 6| 1 of the electromagnetic trip unit may be energized under the control of a conventional overload protective relay, or manually from a remote point by a manual control switch.

The operation of the breaker operating mechl anism is briefly as follows. The circuit breaker is releasably held in closed circuit position as iown in Fig. 1 by the engagement of the pivoted latch 53 with the latch element 5|, which acts to hold the pump piston 33 in the down or cir- 2 cult-closed position, as shown in Fig. 1, against the biasing force of the circuit opening spring 49. The liquid in the lower end of the pump cylinder 3|, and in the liquid carrying conductor 31, and in the lower portions of the operating 2 cylinders 23 acts to hold the operating pistons 25 in their uppermost or closed circuit position.

When the electromagnetic trip unit 51 is energized either in response to a predetermined overload condition, or by the closing of the manual 3 control switch, the trip plunger is moved downwardly, causing the pivoted latch 53 to disengage the latch element 5| thus releasing the connecting rod 45. The circuit opening spring 49 moves the connected pistons 43 and 33 upwardly 3 to their open circuit positions. The upward movement of the pump piston 33 causes movement of the liquid in the upper portion of the pump cylinder 3| into the liquid carrying conductor 35, forcing liquid into the upper ends 4 of the operating cylinders 23 to cause simultaneous downward movement of the operating pistons 25 to their open circuitposition. During this movement, the liquid in the lower portions of the operating cylinders 23 is moved through 4 the liquid carrying conductor 31 into the lower portion of the pump cylinder 3| by the downward movement of the operating pistons 25.

To close the circuit breaker, air under pressure is admitted through the air pressure conductor 5 41 into the upper end of the air pressure cylinder 4|. The air pressure moves the piston 43 and the connected pump piston 33 downwardly to closed circuit position, as shown in Fig. l. The downward movement of the pump piston 5 33 moves the liquid in the lower portion of the pump cylinder 3i into the liquid carrying conductor 31, forcing liquid into the lower portions of the two operating cylinders 23. The operating pistons 25 are simultaneously moved upward- 6 1y to closed circuit position by the liquid, eifecting closing of the breaker.

As has previously been pointed out, it has been found that a certain amount of air may be dissolved in the liquid of the hydraulic operating 5 mechanism. Any air dissolved in the liquid has a tendency to separate out of the liquid whenever the liquid is subjected to a pressure less than atmospheric pressure. A pressure less than atmospheric pressure usually exists on the low pressure side of the hydraulic system during operation of the mechanism. When the air dissolved in the liquid separates out of the liquid, it renders the force transmitting medium in this portion of the hydraulic system compressible to 7 a certain extent, which results in the non-simultaneous operation of the individual pole units of the circuit breaker.

In accordance with the present invention, a means is provided for insuring simultaneous operation of the several poles of the breaker by maintaining the liquid in portions of the hydraulic system under a pressure at least greater than atmospheric pressure, thus preventing any air dissolved in the liquid from separating out of the liquid. This means comprises a container 63 which is disposed at a higher level than the hydraulic system, and which is filled with a liquid of the same composition as is used in the hydraulic system. The container 63 communicates with the liquid carrying conductors 35 and 31, which carry the circuit-opening and circuitclosing liquid, through the agency of liquid conductors 65 and 61, which are of insulating material. A pair of back pressure valves or non-return valves 69 are disposed at the points of communication of the liquid conductor 65 and 61 with the liquid carrying conductors 35 and 31. The nonreturn valves 59 are biased to closed position by means of light springs H. The pressure of the liquid in the container 63 and in the liquid conductors 65 and 6! is supplied through the non.- return valves 69 to the liquid in the two portions of the hydraulic system, and this liquid pressure acts to maintain the portions of the liquid of the hydraulic system at a pressure greater than atmospheric pressure, thus preventing any air dissolved in the liquid of the hydraulic system from separating out of the liquid. The non-return valves 69 prevent the return flow of liquid into the liquid conductors 65 and 61 and the container 63 during operation of the mechanism. When the control pump piston 33 is moved downwardly to effect closing of the breaker, the nonreturn valve 69 in the liquid carrying conductor 31 immediately closes and prevents the flow of the liquid under pressure in the lower portion of the hydraulic system from entering the liquid conductor 65.. At the same time, the non-return valve 65 in the liquid carrying conductor 35 is maintained open by the pressure of the liquid in the container 63 and in the liquid conductor 67, thus maintaining the liquid in the upper portion of the hydraulic system, that is, the portion of the liquid in the upper ends of the operating cylinders 23, in the upper portion of the pump cylinder 3| and in the liquid carrying conductor 35, under a pressure greater than atmospheric pressure, thus preventing any air dissolved in the liquid of this portion of the system from separating out of the liquid. Conversely, when the control pump piston 33 is moved upwardly, the nonreturn valve 39 in the upper liquid carrying conductors 35 immediately closes and prevents the flow of liquid under pressure into the liquid conductor 51. At the same time, the non-return valve 69 in the lower liquid carrying conductor 31 is maintained open, causing the liquid in the lower portion of the hydraulic system, that is, in the lower portion of the pump cylinder 3|, the lower portions of the operating cylinders 23 and in the liquid carrying conductor 31, to be maintained under a pressure greater than atmospheric pressure, thus preventing the air dissolved in the liquid of this portion of the hydraulic system from separating out of the liquid. A conventional expansion vessel for supplying the liquid pressure may be substituted for the separate liquid container 63, if desired.

A modification of the invention is illustrated in Fig. 2 of the drawing. In this modification, the hydraulic operating mechanism is identical to the hydraulic operating mechanism shown in Fig. 1, and hence, the same reference characters have been used to designate the corresponding identical parts. In the embodiment of the invention illustrated in Fig. 2, the means for preventing the air dissolved in liquid of portions of the hydraulic system from separating out of the liquid comprises a liquid conductor 13, containing the same liquid as is present in the hydraulic system, which communicates at its lower end with the liquid carrying conductor 31 through the agency of a non-return valve 69. The opposite end of the insulating liquid conductor 73 communicates with the liquid carrying conductor 35, which carries the liquid for opening the circuit breaker. In this embodiment of the invention the liquid pressure in the conductor 13 is obtained from the high pressure portion of the hydraulic system during an opening operation of the circuit breaker. The diameter of the liquid conductor T3 is considerably smaller than the diameter of the liquid carrying conductor 35 which carries the liquid for opening the circuit breaker so that the presenceof the liquid conductor 13 will not affect the circuit opening operation of the two operating pistons 23.

During opening operation of the circuit breaker, the liquid in the conductor 13 is maintained under pressure, causing the non-return valve 69 to remain open and subjecting the liquid in the lower portion of the hydraulic system, that is, the circuit closing liquid, under a pressure greater than atmospheric pressure, thus preventing any air dissolved in this portion of the liquid from separating out of the liquid. During closing of the circuit breaker, the pressure in the lower portion of the hydraulic system maintains the nonreturn valve 69 closed, preventing any return flow of liquid intothe liquid conductor 13.

If desired, a second liquid conductor similar to the conductor 13 may be provided between the liquid carrying conductors 35 and 31, and a nonreturn valve disposed at the point of communication of this second liquid conductor, to the liquid carrying conductor 35. This second liquid conductor and non-return valve will operate during closing operations of the breaker to maintain the liquid in the upper portion of the system, that is the circuit-opening liquid, under a pressure greater than atmospheric pressure, thus preventing any air dissolved in the liquid of the upper portion of the hydraulic system from separating out of the liquid.

The present invention constitutes a continuation-in-part and an improvement of the invention disclosed and claimed in the copending application of Fritz Kesselring et al., Serial No. 254,614, referred to above.

Although the invention has been disclosed as embodied in a hydraulic operating mechanism of a particular construction, it is to be understood that it is equally applicable to any other type of hydraulic operating mechanism for a multi-pole circuit breaker where separate operating devices are provided for each pole of the breaker.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is .to be understood that various changes in the structural details thereof may be made without departing from the spirit of the invention. It is desired, therefore, that the language of the appended claims be given the broadest reasonable construction permissible in the light of the prior art.

I claim as my invention:

1. In combination, a multipole circuit interrupter having a plurality of movable contact members, an individual hydraulically actuated operating means for moving each contact member, hydraulic actuating means for controlling movement of said individual operating means, liquid carrying conductor means connecting said hydraulic actuating means and said operating means, and means eifective in all positions of said hydraulic actuating means for preventing portions of the liquid in said system from being subjected to a pressure less than atmospheric pressure, thus preventing air dissolved in the liquid from leaving the liquid.

2. In combination, a multipole high voltage circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said individual operating means, and means effective in all positions of said liquid moving means for preventing portions of the liquid in said system from being subjected to a pressure less than atmospheric pressure.

3. A multipole high voltage circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said individual operating means, and means for preventing portions of the liquid of said system from being subjected to a pressure less than atmospheric pressure, thus preventing air dissolved in the liquid from coming out of the liquid.

4. A multipole high voltage circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said individual operating means, and means connected to said liquid carrying conductor means eifective in all positions of said liquid moving means for preventing portions of the liquid from being subjected to a pressure less than atmospheric pressure.

5. A multipole circuit breaker having a plurality of moving contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said operating means, and means comprising a source of liquid pressure connected to said liquid carrying conductor means for preventing portions of the liquid of the hydraulic system from being subjected to a pressure less than atmospheric pressure, thus preventing air dissolved in the liquid from coming out of the liquid.

6. A multipole circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, said individual operating means each including an operating cylinder containing liquid, and a liquid operated piston in said cylinder connected to its movable contact member, a

liquid moving means for controlling the operation of said liquid actuated operating means, liquid carrying conductors connecting said liquid moving means to the opposite ends of said individual operating cylinders, and means comprising a liquid container communicating through a liquid conductor and a non-return valve with at least one of said liquid carrying conductors for preventing portions of the liquid in the hydraulic system from being subjected to a pressure less than atmospheric pressure.

7. A multipole circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, said individual operating means each comprising an operating cylinder containing liquid and a liquid operated piston in said cylinder connected to its movable contact member, a liquid moving means for controlling the operation of said liquid actuated operating means, liquid carrying conductors connecting said liquid moving means to the opposite ends of said individual operating cylinders, and means comprising a liquid container communicating through liquid conductors and nonreturn valves to said liquid carrying conductors for preventing the liquid in the hydraulic system from being subjected to a pressure less than atmospheric pressure.

8. A multipole circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, said individual operating means each comprising an operating cylinder containing liquid and a liquid operated piston in said cylinder connected to its movable contact member, a liquid moving means for controlling the operation of said liquid actuated operating means, liquid carrying conductors connecting said liquid moving means to the opposite ends of said individual operating cylinders, and means comprising a conductor containing liquid communicating at one end through a nonreturn valve to at least one of said liquid carrying conductors and communicating at its other end with an expansion vessel, said last-mentioned means preventing portions of the liquid the hydraulic system from being subjected to a pressure less than atmospheric pressure.

9. A multipole circuit breaker having a plurality of moving contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said operating means, and means comprising a liquid container coinmunicating through a liquid conductor and through non-return valves with said liquid carrying conductor means for maintaining at least portions of the liquid in the hydraulic system under a pressure greater than atmospheric pressure.

10. A multipole circuit interrupter having a plurality of movable contact members, an individual liquid actuated operating means for moving each contact member, said individual operating means each comprising an operating cylinder containing liquid and a liquid operated piston in said cylinder connected to its movable contact member, liquid moving means for controlling the operation of said liquid actuated operating means, liquid carrying conductors connecting said liquid moving means to the opposite ends of said individual operating cylinders,

and means comprising at least one liquid conductor connecting said liquid carrying conductors and communicating with one of said liquid carrying conductors through a non-return valve, said last-mentioned means maintaining portions of the liquid of the hydraulic system under a pressure greater than atmospheric pressure, thus preventing air dissolved in the liquid from separating out of the liquid.

11. A multipole circuit breaker having a plurality of moving contact members, an individual liquid actuated operating means for moving each contact member, liquid moving means for controlling the operation of said operating means, liquid carrying conductor means connecting said liquid moving means to said operating means, and means comprising a source of liquid pressure connected to said liquid carrying conductor means for preventing portions of the liquid in the hydraulic system from being subjected to a pressure less than atmospheric pressure, thus preventing air dissolved in the liquid from coming out of the liquid, and a non-return valve in the connection of said source of liquid pressure to said liquid carrying conductor.

PAUL DiiFFING. 

